The rainbow links the New Jerusalem to heaven1, from which descends toward the prophet the dove, symbolizing the Holy Ghost, while angels direct to him the sound of their trumpets.
This instrument is always associated with the divine messages ("And he will send out his angels with a loud trumpet call”, Matthew 24:31, and "Blessed is the people that know the joyful sound" [of the trumpet]", Psalm 89:15)2 which allows Swedenborg to develop his doctrine, based on what had been heard from heaven3, unveiling to him the truth of the Scriptures.
Nicolaas Urban describes the painting with these words: "[…] Emmanuel [sic] Swedenborg in the centre of heaven – hears the words of the Lord, with Holy Jerusalem in the background and the rainbow – which tells us that the Lord never forgets his poor children. Certainly the reproduction is bad and does not convey the values of such a noble painting, but despite everything, when you see his figure of wisdom which rises to heaven like the sun in the morning, the only hope; the only truth; the only relief; the apotheosis which sweeps away all the tears of the two other paintings! […]"4
1. "And I saw the holy city, new Jerusalem, coming down out of heaven from God, ...", Revelation 21:2, English Revised Version.
2. English Revised Version.
3. Emanuel Swedenborg, Of the New Jerusalem and its heavenly doctrine, as revealed from heaven, Boston: O. Clapp .
4. "[…] Emmanuel [sic] Swedenborg/ au milieu du ciel - entend les/ paroles du Seigneur, avec la/ Sainte Jérusalem au fond et/ l'arc en ciel – qui nous dit que/ le Seigneur n'oublie jamais ses/ pauvres enfants. Certainement que la reproduction est mauvaise et ne donne pas les valeurs de la peinture si noble, mais malgré tout, si tu vois sa figure de sagesse qui se lève au ciel comme le soleil au matin, le seul espoir; la seule vérité; le seul secours; l’apothéose qui efface toutes les larmes des deux autres tableaux! […]" (Nicolaas Urban, ALS to Philippe Smit, Ceray [Céré-la-Ronde], [Indre], Christmas 1941, private archives, Paris, reply upon receiving from Philippe Smit at Christmas three reproductions of his latest works [PS 485], [PS 473] and [PS 486]).